initial battery work

src/machine/battery.rs

+use crate::power::{Capacity, Source};
+
+use bevy::prelude::*;
+
+#[derive(Bundle)]
+pub struct BatteryBundle {
+    pub source: Source,
+    pub capacity: Capacity,
+}

src/machine/mod.rs

@@ -7,6 +7,7 @@ use crate::{
 use bevy::prelude::*;
 
 mod cable;
+mod battery;
 
 pub const MACHINE_SIZE: Vec2 = Vec2::new(GRID_SIZE.x / 8.0, GRID_SIZE.y / 8.0);
 

src/power.rs

@@ -17,6 +17,9 @@ impl Plugin for PowerPlugin {
     }
 }
 
+#[derive(Component, Copy, Clone, Debug, Deref)]
+pub struct Capacity(pub f32);
+
 /// Any entity that can emit power (a generator, cable, etc.) should have
 /// source as one of it's components. The output field defines in which directions
 /// the entity may output power and the power field controls the amount of